The present invention is directed to a hand-held tool with a holder for tool bits and a probing device for checking the surface configuration of the tool bit for effecting a switching procedure of the tool operation.
An electrically driven hand-held tool in the form of a drill is disclosed in DE-OS 29 43 508 and carries out a switching operation controlled by the surface configuration of inserted tool bits with the switching procedure providing the appropriate operation of the tool. The surface configuration of the tool bit is determined mechanically by a probing device including a displaceable pin, which effects the variable displacement of the probing device. An electrical regulator is adjusted by the probing device in accordance with the displacement travel and, in turn, switches the drive of the hand-held tool to the desired value.
The surface contour of the tool bit which determines the desired operation is located at the forward region of a threaded sleeve extending in the insertion direction of the tool bits. The threaded sleeve is bolted to an adapter in which a bit is clamped. The tool parts consisting of the threaded sleeve, the adapter and drill bit are retained in the tool holder of the hand-held tool so as to be exchangeable by a rapid action lock. The threaded sleeve is moved into an appropriate axial position relative to the adapter before the tool bit is inserted into the holder for determining the desired tool operation.
Such tool bit dependent control is not suitable for hand-held tools, such as hammer drills, which direct axial blows against the tool bit, since such blows result in an intermittent axial movement of the tool bits. The axial movement of the tool bits would be transferred to the probing device and would render the control of the tool operation impossible.